Knock, knock.... grrrr

[Injuneer]

Do you have a log with it at WOT? Why are you logging at only about 70+% throttle? Do you get the same results at 100% TPP?

Looks possibly like some sort of sudden mechanical noise... e.g. headers hitting the frame or steering, motor mount rattling, etc. Another possibility would be some high voltage interference that is entering the knock sensor wiring. Do you have any plug wires real close to the knock sensor or KS wire harness?

[Formulaboy95]

Same results at 100% WOT... Thing that gets me is that it is always at 4100/4200 rpms. The chance of metal banging at that exact rpm seems kinda slim, especially every time. The logs are from today, and it's too cold to attempt going too fast on cold DR's in this weather.

Would lack of a spark cause knock? Say if the opti cap&rotor section had some corrosion inside from moisture.

I wonder if I it will show up if I rev to 4100 with the car not moving.... hmm... SLP LM + SLP Headers... The neighbors are gonna love this.

[Injuneer]

Some of this may be odd, but you've apparently checked all the obvious stuff. Perhaps the engine vibration hits a harmonic at 4100rpm and it is enough to vibrate the exhaust or a motor mount. Perhaps the induced high voltage pulses from a misplaced wire are affecting the knock sensor circuit at a fequency that is generated at 4100rpm....

Just trying to give you some examples of things I have found in the past.